JPH04314902A - Governor follow-up device for back pressure turbine - Google Patents

Abstract

PURPOSE:To prevent increase of a rotational number of a back pressure turbine during shifting from a pressure governing operation to a speed governing operation, and also prevent a remarkable change of a back pressure by adding a bias signal from a bias setter to a sum of a load setting signal and a speed controlling signal during the pressure governing operation, and providing a means for subtracting the bias signal during the speed governing operation. CONSTITUTION:A motion controlling system B is provided with a bias setter 18, an adder 19 and a pressure governing operation contact point 20. The bias setter 18 outputs a specified value of bias signal S10. The adder 19 adds the bias signal S10 from the bias setter 18 during a pressure governing operation. The pressure governing operaction contact point 20 is closed during the pressure governing operation, and opened during parallel off. When the pressure governing operation is changed over to a speed governing operation by the parallel off, the pressure governing operation contact point 20 is opened. Thus, the bias signal S10 is not input to the adder 19, and a back pressure controlling signal S8 is not input to a lower value preference circuit 12. As a result, a speed governing controlling signal S11 speedily approaches a level of the back pressure controlling signal S8 during the pressure governing operation, and follows it Up.

Description

[Detailed description of the invention]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a governor follow-up device for a back pressure turbine that performs pressure regulating operation to keep back air pressure constant.

0002

BACKGROUND OF THE INVENTION Conventionally, during parallel operation, back pressure turbines are operated to adjust their pressure to keep the back air pressure constant. At this time, the governor position is set to the upper limit. That is, during the above-described pressure regulating operation, the amount of steam flowing into the turbine is controlled based on a back pressure control signal obtained by comparing the back air pressure and the back pressure set value.

On the other hand, when the synchronization to the grid is discontinued, the system switches to speed-governing operation and the load setting device controls the flow of steam into the turbine based on the sum of the load setting signal and the speed control signal of the speed control circuit. The amount is controlled.

FIG. 3 shows a governor follower for the above-mentioned general back pressure turbine.

In the operation system A of the back pressure turbine, steam from the boiler is adjusted to a predetermined amount by a steam control valve 1. The steam that has done work in the back pressure turbine 2 passes through the back air path and is used as process steam. The turbine generator 3 is coupled to the back pressure turbine 2 and is rotationally driven by the back pressure turbine 2 to generate electricity.

On the other hand, in the operation control system B of the back pressure turbine 2, an electromagnetic detector 5 installed opposite a gear 4 directly connected to the turbine shaft detects the rotation speed of the back pressure turbine 2 as a frequency signal. The frequency-voltage converter 6 that receives this frequency signal outputs an analog voltage signal proportional to the frequency as the speed signal S1. This speed signal S1 is compared with the speed setting signal S2 from the speed setter 7 by an adder 8, and the deviation signal S3 is inputted to the speed control circuit 9.

In the speed control circuit 9, the speed control signal S4 is converted into a speed control signal S4 according to the speed adjustment rate, and the speed control signal S4 is input to the adder 10. The adder 10 adds the load setting signal S5 of the load setting device 11 and the speed control signal S4, and outputs the result as a speed governor control signal S6.

Next, in the low value priority circuit 12, the speed governor control signal S6, the load limit signal S7 output from the load limit circuit 13, and the back pressure control signal S8 output from the back pressure setting circuit 14 are compared. The signal with the lowest value among these signals is output to the steam control valve control circuit 15 with priority.

The valve control signal S9 outputted from the steam control valve control circuit 15 is converted into a mechanical signal by the electro-mechanical signal converter 16, and drives the lever of the hydraulic cylinder 17. Thereby, the amount of steam entering the back pressure turbine 2 is controlled by opening and closing the steam control valve 1. In this way, speed control, load limiting or back pressure control of the steam turbine is achieved.

By the way, during pressure regulating operation, the load setting signal S5 of the load setting device 11 is set to the upper limit, and when switching to speed regulating operation at the time of disconnection, the back pressure control signal S8 and speed regulating operation during pressure regulating operation are set to the upper limit. Since there is a large difference between the control signal S6 and the control signal S6, the rotational speed and back air pressure of the steam turbine will vary greatly. Therefore, during pressure regulation operation, the back pressure control signal level follows the load setting signal of the load setting device with a certain margin to suppress the sudden increase in the speed of the steam turbine and the fluctuation of the back air pressure when the train is disconnected. controlled to do so.

[0011]

[Problem to be Solved by the Invention] However, as mentioned above, since a margin value is provided in consideration of the case where the back pressure control signal fluctuates, when switching to speed regulating operation at the time of train disconnection, it still depends on the margin width. There are problems in that the rotational speed increases and the back air pressure fluctuates at low levels.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a governor follow-up device for a back pressure turbine that can prevent an increase in rotational speed and fluctuations in back air pressure during parallel disconnection.

[Configuration of the invention]

[Means for Solving the Problems] During pressure regulating operation, the present invention provides a back pressure control signal based on the deviation between the back air pressure of the back pressure turbine and the back pressure setting value, and a load setting signal of the load setting device. The low value priority circuit inputted with the speed governor control signal obtained by adding the control signal outputs the back pressure control signal, and sets a predetermined tracking width to this back pressure control signal so that the speed governor control signal follows and adjusts. In a governor follower for a back pressure turbine, the governor follower for a back pressure turbine is configured to perform pressure control and, during speed governing operation, to perform speed governing control using the speed governing control signal from the low value priority circuit. a bias setter for setting the value to be almost the same as the value of the back pressure control signal, while providing the predetermined follow-up width to a signal obtained by adding the speed control signal to the load setting signal; and a bias setting device for setting the speed control signal to the load setting signal. The bias signal from the bias setting device is added to the signal obtained by adding the bias signal during pressure regulating operation, and is removed during speed regulating operation.

[0014]

[Operation] With the above configuration, it is possible to prevent changes in the valve opening degree when transitioning to speed regulating operation by automatically making the load setting signal of the load setting device follow the level of the back pressure control signal during pressure regulating operation. . Therefore, regardless of the state of the pressure regulating operation, it is possible to prevent an increase in the rotational speed and a fluctuation in the back air pressure when the train is disconnected.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial block diagram of a governor follower for a back pressure turbine showing an embodiment of the present invention. The same reference numerals as in FIG. 3 indicate the same or equivalent parts. Figure 3
The difference is that the operation control system B is newly equipped with a bias setting device 18, an adder 19, and a pressure regulating operation contact 20. In this embodiment, during pressure regulation operation, a signal obtained by adding a speed control signal, a load setting signal, and a bias signal is used as a speed control signal, while when disconnecting, a speed control signal to which a bias signal is not added is used as a speed control signal. I try to control it.

Bias setting unit 18 outputs a bias signal S10 having a predetermined value.

The adder 19 adds the bias signal S10 of the bias setter 18 during pressure regulation operation.

The pressure regulating operation contact 20 closes during the pressure regulating operation, and opens when the series is disconnected.

With the above configuration, the rotation speed of the back pressure turbine 2 is outputted to the adder 8 as a speed signal S1. In the adder 8, the deviation signal S3 with respect to the speed setter 7 is inputted to the speed control circuit 9, where it is converted into a speed control signal S4 according to the speed adjustment rate. This speed control signal S4 is added with a load setting signal S5 from a load setting device 11 in an adder 10, and is outputted to an adder 19 as a speed governor control signal S6.

During the pressure regulating operation of the back pressure turbine 2, the level of the load setting signal S5 of the load setting device 11 is synchronized with the level of the back pressure control signal S8. Furthermore, during the pressure regulation operation, the pressure regulation operation contact 20 is closed, and the bias signal S10 from the bias setting device 18 is input to the adder 19. Then, the speed regulating control signal S1 is output from the adder 19.
1 is input to the low value priority circuit 12.

As shown in FIG. 2A, the low value priority circuit 12 receives the speed governor control signal S11, the load limit signal S7 from the load limit circuit 13, and the back pressure control signal S8 from the back pressure setting circuit 14. is input. In this state, the speed governor control signal S11 is a value obtained by adding the bias signal S10 to the speed governor control signal S6, which is the sum of the speed control signal S4 and the load setting signal S5, and the load A limit signal S7 is located.

The back pressure control signal S8 selected by the low value priority circuit 12 is input to the steam control valve control circuit 15, which outputs the valve control signal S9 to the electro-mechanical signal converter 16. The electro-mechanical signal converter 16 drives the hydraulic cylinder 17,
Controls the opening and closing of the steam control valve 1.

Here, as shown in FIG. 2(B), when the pressure regulating operation is being carried out from time t0 to time t1, when switching to speed regulating operation due to disconnection, the contact 20 for pressure regulating operation is opened and the bias is applied. Signal S10 is no longer input to adder 19. Further, the back pressure control signal S8 is no longer input to the low value priority circuit 12. As a result, as shown in the figure, the speed regulating control signal S11 quickly approaches and follows the level of the back pressure control signal S8 during the pressure regulating operation. Therefore, it is possible to prevent fluctuations in the valve opening degree at the time of disconnection.

[0025] During pressure regulation operation, the pressure regulation operation contact 20
is closed, and the regulating control signal S11 is the bias signal S1
Since 0 is added, even if the back pressure control signal S8 fluctuates, there is no switching to speed regulating control.

As described above, according to this embodiment, the level of the load setting signal of the load setting device is made to follow the back pressure control signal during the pressure regulating operation of the back pressure turbine. Therefore, no matter what operating state there is a switch to speed governing operation, bumpless transition to speed governing control is possible. Therefore, it has the excellent effect of being able to prevent an increase in the rotational speed and a large fluctuation in back air pressure when switching to speed control operation.

[0027]

As described above, according to the present invention, the load setting signal of the load setting device can be made to follow the level of the back pressure control signal during the pressure regulating operation when switching to the regulating operation. Thereby, it is possible to suppress an increase in the rotational speed of the back pressure turbine and a large fluctuation in the back air pressure at the time of transition from pressure regulating operation to speed regulating operation.

[Brief explanation of drawings]

FIG. 1 is a partial block configuration diagram of a governor follower device for a back pressure turbine showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing each control signal of the device.

FIG. 3 is a block configuration diagram of a governor following device for a back pressure turbine showing a conventional example.

[Explanation of symbols]

1 Steam control valve 2 Back pressure turbine 3 Turbine generator 7 Speed setting device 8 Adder 9 Speed control circuit 10 Adder 11 Load setting device 12 Low value priority circuit 13 Load limiting circuit 14 Back pressure setting circuit 15 Steam control valve control circuit 18 Bias setting device 19 Adder 20 Contact for pressure regulation operation

Claims (1)

[Claims] Claim 1: During pressure regulating operation, speed regulating control is performed using a back pressure control signal based on the deviation between the back pressure of the back pressure turbine and the back pressure set value, and a speed control signal added to the load setting signal of the load setting device. The low value priority circuit inputting the signal outputs the back pressure control signal, and the speed governor control signal follows the back pressure control signal with a predetermined follow-up width to perform pressure regulation control. During operation, in a governor follower of a back pressure turbine configured to perform speed governing control using the speed governing control signal from the low value priority circuit, the load setting signal of the load setting device is set approximately equal to the value of the back pressure control signal. a bias setting device for setting the predetermined follow-up width to a signal obtained by adding the speed control signal to the load setting signal, and a bias setting device for setting the bias to the signal obtained by adding the speed control signal to the load setting signal; A governor follow-up device for a back pressure turbine, characterized in that it is provided with means for adding a bias signal from a regulator during pressure regulating operation and excluding it during speed regulating operation.